In recent years, an output of a semiconductor laser device has been remarkably enhanced. In the field of industrial applications, the semiconductor laser device is expected as a light source for a processing device for carrying out processing (for example, welding, joining, and cutting) by laser light.
Since a large number of semiconductor laser elements can be simultaneously produced from a semiconductor wafer, each semiconductor laser element has a small size, and the production efficiency of semiconductor laser elements is high. Therefore, the semiconductor laser element is suitable for a small-size light source of laser light for a semiconductor laser device in several-tens-of-W class. As the light source for such a high-output semiconductor laser device, a combination of a plurality of single-type semiconductor laser elements, and an array-type semiconductor laser element are used. The array-type semiconductor laser element includes a plurality of adjacent active regions in one chip, and a plurality of light-emission points called emitters, which are adjacent to each other, on one end surface of the chip. The single-type semiconductor laser element has one emitter on the end surface of the chip.
Furthermore, laser light emitted from the semiconductor laser device can be collected into a region of about several microns. Therefore, a semiconductor laser device capable of focusing energy of laser light on an extremely small region is suitable for local processing.
However, a semiconductor laser device used for processing is operated at output power of about 10 W to several tens of W. Therefore, an electric current necessary for operation is extremely large and an amount of heat generated in an active region of the semiconductor laser element is also extremely large as compared with those in a semiconductor laser device used for an optical disk and the like having output power in several-hundred-of-mW class. Therefore, in order to maintain a semiconductor laser device used for processing at high output with high reliability, and to operate the semiconductor laser device for a long lifetime, it is important to rapidly dissipate heat generated in the active region of the semiconductor laser element to the outside so as to suppress the temperature increase in the active region.
Patent Literatures 1 to 3 have proposed a semiconductor laser device having a structure for promoting heat dissipation of a chip. A conventional semiconductor laser device of PTL 3 is described with reference to FIG. 9.
FIG. 9 is a perspective view of conventional semiconductor laser device 900. As shown in FIG. 9, in conventional semiconductor laser device 900, semiconductor laser element 901 is packaged on heat sink 903 via solder layer 902.
Conventional semiconductor laser device 900 emits laser light 904 from a laser-emitting surface of semiconductor laser element 901, which corresponds to the forward side of FIG. 9. In the conventional semiconductor laser device 900, semiconductor laser element 901 is joined to heat sink 903 with solder layer 902 such that the laser-emitting surface of semiconductor laser element 901 is positioned in the same plane as the side surface of heat sink 903.
With this configuration, laser light 904 emitted from the laser-emitting surface of semiconductor laser element 901 is not interrupted by heat sink 903. Furthermore, heat of semiconductor laser element 901 is sufficiently dissipated by heat sink 903.
Furthermore, PTL 4 has proposed a light source device in which a function of cooling a laser diode array is enhanced by providing a passage of cooling water inside the cooling device on which laser diode array is mounted.
Furthermore, PTL 5 has proposed an electronic apparatus including a liquid cooling system. In particular, PTL 5 has proposed preventing of corrosion in a system in which aluminum and copper are present together, by adding a corrosion inhibitor to a cooling liquid and providing ion-exchange resin which has adsorbed the corrosion inhibitor.